Acute stress effects on local Il-1beta responses to pathogens in a human in vivo model

The combined effects of stress and antigen on interleukin-1beta (Il-1beta) have rarely been studied locally at the site of microbial challenges in vivo, so far. We here propose a model for the analysis of such effects in humans and examine its utility for acute stress trials. Twelve students (6 male, 6 female) refrained from oral hygiene in two antagonistic quadrants for 28 days to allow for increasing bacterial stimulation of the respective gingival sites due to accumulation of microbial plaque. Good oral hygiene was maintained in the remaining quadrants. At day 27 and 28 students were subjected to either stress ('public speech') or a control condition, in a cross-over design. Samples of gingival crevicular fluid (GCF) which emerges between the tooth surface and the gingival epithelium as transudate of healthy and exudate of inflamed gingival tissue, were taken immediately after stress and 60 min later for Il-1beta analysis. Salivary cortisol was assessed to prove the validity of the stress protocol. Stress induced a profound increase of salivary cortisol (p=.001). Repeated measures (stress x time x hygiene) ANOVA with gender as between factor revealed significant stress (p=.014) and hygiene (p=.038) effects on GCF-Il-1beta concentrations and tentatively significant hygiene x time (p = .097) and stress x time x hygiene x gender (p=.107) interactions. Stress induced an increase of Il-1beta as did plaque accumulation. The merits of the proposed model are discussed. It is concluded that it is well suited for the assessment of the effects of stress on inflammatory responses in vivo in humans.